<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        .box{
            width: 100px;
            height: 100px;
            background-color: red;
            /* transition: 属性 花费时间 运动曲线 何时开始; */
            transition: width 1s ease 0s, height 1s ease 0s;
        }
        .box :hover
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>